Combustors used in gas turbines are classified into a gas combustion type, an oil combustion type, and a dual type, which is a combination of the gas combustion and oil combustion types. Among them, the oil combustion type or dual type combustor is equipped with a fuel oil supply system in order to supply fuel oil to a plurality of nozzles arranged around the central axis of the combustor. The fuel oil supply system includes a plurality of oil supply tubes and an oil chamber. Each of the oil supply tubes connects the base end of each nozzle to the oil chamber. The oil chamber is formed inside a nozzle tube base supporting the base end of each nozzle, and communicates with each nozzle via each supply tube.
In the oil combustion type or dual type combustor, when oil combustion is stopped or oil combustion is switched to gas combustion in the dual type, the fuel oil from the oil chamber of the combustor needs to be sufficiently removed. This is because the fuel oil inside the oil chamber is carbonized (caulked) due to heat transferred from a casing and there is a possible that the carbonized fuel oil blocks the oil supply tube or the fuel oil ejection portion at the front end of the nozzle when the fuel oil remains in the oil chamber. When the oil supply tube or the fuel oil ejection portion is blocked, the gas turbine needs to be cleaned during stopping the operation thereof. For this reason, the operating efficiency of the gas turbine degrades.
In the following Patent Literature 1, the oil chamber is formed to have a cross-star-shaped cross-section when viewed in the axial direction, fuel is transferred on a curved surface forming the inner wall of the oil chamber to be guided toward the supply path, and the fuel is blown away by compressed air to be discharged to the outside, thereby reducing the amount of the fuel remaining inside the oil chamber.